1. Technical Field
This document relates to methods and materials involved in reducing biofilms. For example, this document provides enzymes (e.g., glycosyl hydrolases) and methods for using enzymes to reduce biofilms.
2. Background Information
Bacteria growing in biofilms are estimated to be involved in greater than 60 percent of all human bacterial infections. Biofilms are dynamic populations of bacteria in a surface-associated mode of growth that are covered in a protective, self-excreted extracellular polymeric substance (EPS) matrix. Biofilms provide protection against harsh environmental conditions, traditional antimicrobial therapies, and host immune defenses, thus making biofilm-associated infections difficult to treat. Biofilm-associated infections of indwelling medical devices (e.g., intravascular and urinary catheters, prosthetic heart valves, prosthetic joint implants, and hardware) represent a particularly important health problem, as removal and replacement of infected devices is often required.
The EPS matrix of a diverse number of biofilm-forming bacterial species can be composed of chains of polymeric β-1,6-linked N-acetyl-glucosamine (PNAG). Biofilm-forming strains of Staphylococcus aureus, S. epidermidis, Bordetella spp., Actinobacillus spp., and Escherichia coli are known to utilize PNAG as a major component of their EPS biofilm matrix (Cramton et al., Infect. Immun., 67:5427-5433 (1999); Kaplan et al., J. Bacteriol., 186:8213-8220 (2004); Mack et al., J. Bacteriol., 178:175-183 (1996); Parise et al., J. Bacteriol., 189:750-760 (2007); and Wang et al., J. Bacteriol., 186:2724-2734 (2004)). The N-acetyl-β-hexosaminidase, dispersin B, first purified from the Gram negative periodontal pathogen Actinobacillus actinomycetemcomitans (Kaplan et al., J. Bacteriol., 185:4693-8 (2003)), can cleave the β-1,6-linkages of PNAG in the biofilm matrices of Staphylococcus spp., Yersinia pestis, Actinobacillus spp., Bordetella spp., and E. coli (Itoh et al., J. Bacteriol., 187:382-387 (2005); Kaplan et al., J. Bacteriol., 185:4693-8 (2003); Kaplan et al., Antimicrob. Agents Chemother., 48:2633-2636 (2004); Kaplan et al., J. Bacteriol., 186:8213-8220 (2004); and Parise et al, J. Bacteriol., 189:750-760 (2007)).